There is a widely known material for producing pyrometric refractory components (cf. British Pat. No. 1,281,718; 1973).
This material contains zirconium dioxide stabilized with calcium oxide. Pyrometric refractory components (solid electrolytes, protective caps, jackets, etc.) are made of this material in a conventional manner, in the shape of tubes with a sealed end.
The above material and process for producing pyrometric refractory components thereof, however, do not provide for their stability to rapid heating at elevated temperatures (above 1,000.degree. C.) and reliability, i.e. a high ratio of the number of successfully tested pyrometric refractory components to the total number of tested components, in %.
Also known is a material for pyrometric refractory components (cf. U.S. Pat. No. 3,674,654; 1972) fabricated in a conventional manner from zirconium dioxide stabilized with beryllia.
This material and the associated process for producing pyrometric refractory components also fail to provide for adequate reliability and stability of such components heated to temperatures of up to 1,600.degree. C.
Another known material for pyrometric refractory components manufactured in a conventional manner, is based on beta alumina (cf. U.S. Pat. No. 3,687,735). The disadvantages of this material and the associated process for producing pyrometric refractory components are the same as in the case of the previously mentioned two other materials and processes.
Yet another material for pyrometric refractory components is known (cf. U.S. Pat. No. 4,067,792), containing alumina, zirconium dioxide and titanium dioxide in the following ratio, % by weight:
______________________________________ alumina 85 to 95 zirconium dioxide 4 to 10 titanium dioxide 1 to 5. ______________________________________
The material is used in producing pyrometric refractory components each being in the form of a tube with a sealed end, which are employed in devices for determining the oxidized state and temperature of molten metal.
The process for producing these pyrometric refractory components comprises mixing of finely divided ingredients: alumina, titanium dioxide and zirconium dioxide, introduction of a plasticizing additive into the resulting mixture, moulding of the component, drying at a temperature of 200.degree. C., and firing at a temperature of 1,600.degree. to 1,650.degree. C., the ingredients being mixed in the following ratio, % by weight:
______________________________________ alumina 85 to 95 titanium dioxide 1 to 5 zirconium dioxide 4 to 10. ______________________________________
However, the above material and process do not provide for the required high stability to rapid heating at temperatures ranging from 1,650.degree. to 1,750.degree. C., as well as for adequate overall and ionic conductivity of the material at low partial oxygen pressures in the ambient medium of 10.sup.-12 to 10.sup.-13 atm.